Cor, Blimey Guv'nor! It's the English/Cockney Rhyming Slang Dictionary! Very useful if you don't know your John Cleese's from your Duke of Kent's. Once you've mastered the art, you'll have no trouble understanding this passage.
Everyone wants to be l33t. Now it's even easier with this handy guide.
Just in case you're in Britain and happen to commit a felony, don't be caught unprepared. Visit the site of HM Prison Service and get up to date with your British prisoner slang.